Coil system and coupling apparatus



Aug. 19, 1930. L. L. JONES COIL SYSTEM AND COUPLING APPARATUS Original Filed July 19, 1926 avwemboz Leskr Ln ones Patented Aug. 19, 1930 LESTER L. JONES, OF ORADELL, NEW JERSEY COIL SYSTEM AND COUPLING AP PABATUS Original application filed July 19, 1926, Serial No. 123,346. Divided and this application tiled September 82, 1927. Serial No. 221,259.

This invention relates to an inductance coil system and relates more particularly to a coil system especially designed for radio circuits of the sharply tuned or selective type; and has special reference to the provision of a coil system which is magnetically self shielded and to coupling apparatus especially designed for use therewith. i

This application is a division of my com pending application, Serial N o. 123,346,.filed July 19, 1926 to radio frequency amplifying systems.

One of the important problems in the design of certain types of selective and sensitive radio'receiving apparatus and in apparatus employable near transmitting stations is the construction of the inductance coils and variable or non-variable coupling apparatus or transformers forming part of the radio receiving apparatus so that these coils or transformers are uncoupled magnetically to other coils and similar apparatus in the receiving set, or to the transmitting apparatus. To accomplish the magnetic uncoupling of the coils to other and adjacent apparatus various types of coil windings have heretofore been suggested and designed, such as double D windings, toroid windings and bifilar coils. These prior types of coil windings have, however,

been found insufficient-to produce the de-' sired results 'on account of their relatively large external fields near the coil which produces considerable coupling to other, apparatus and evenbetween similar coils when placed 5, at a moderate distance apart such as is commonly met with in ordinary receiving sets.

To reduce the inter-magnetic couplings between similar coils in the radio'receiving set with the use of such prior structures it has 40 been found necessary to so relatively arrange the coils one with respect to the other in the radio receiving set as to minimize the reacting fields. Other structural difiiculties,

' such as the large volume of winding required \and the difliculty of winding methods have also hindered the use of these, prior and known types of winding coils.

A prime desideratum of my present invention resides in the provision of an inductance coil system designed and constructed so that Renewed January 10, 1930.

the external magnetic field is reduced to such a minimum that the coil is substantially decoupled magnetically from surrounding apparatus and may be placed in close proximity to other similar coils of a radio receiving system without inter-magnetically reacting with the same.

A further prime desideratum of my present invention resides in the provision of a coupling apparatus or transformer embodying such an inductance coil system designed and constructed as aforesaid to minimize the external magnetic field, the said coupling apparatus beingconstructed however to permit a wide range of inductive coupling to be made to the inductance coil system from substantially zero coupling to a substantially high maximum coupling.

An important and corelated object of vthe invention centers about the provision of a coil system and coupling apparatus of the type referredto which is exceedingly simple in construction permitting standard and facile winding methods to be employed in the making thereof and enabling the use of ordinary simply constructed winding forms to be employed therewith.

To the accomplishment of the foregoing and such other objects as will hereinafter appear, my invention consists in the elements and their relation one to the other as hereinafter more articularly described and sought to be defined in the claims, reference being had to the accompanying drawing which shows the preferred embodiment of my invention, and in which The figure is a cross-sectional view of the coil system and coupling apparatus embodying the principles of my invention and showing the manner of connecting the same in a radio circuit.

Referring now more in detail to the drawings, the coil system of my invention is shown in the form of a secondary S of a transformer having a primary P, the said secondary S embodying a plurality of coil sections S and S so related that while the coil sections in combination produce a resultant inductance of substantial magnitude, the coil system as a whole is substantially decoupled magnetically from other apparatus, the coil sections thereof being interrelated to produce neutralizing magnetic fields at a distance.

F or producing the most simple construction the winding form used is a single cylinder or drum 10; and when wound on such a drum the coil sections S and S are arranged coaxially as shown and have substantially equal average diameters and areas. The coil sections S and S are wound in opposite directions so that oppositely directed fluxes for the coil S and S are produced. Where the average diameter or area of the coil S is the same as that of the coil S as shown in the drawings, the coil sections S and S are each provided with the same number of turns or windings so that the product of the area and number of turns of the coil section S is substantially equal to the product of the numoer of turns and area of the coil section S To produce a resulting inductance for the coil system of a substantial order of magnitude, the coil sections S and S are separated or spaced a distance apart as indicated by the arrowed line b; and for the purpose of effecting the desired neutralization of the magnetic fields at a distance so as to produce the desired magnetic decoupling characteristic of the coil system, the distance 6 is made Suficiently small so that the fluxes produced by the coil sections S and S at any surrounding point in space at a moderate distance from the coil system are in substantially diametrically opposing relation. 1 have empirically found that the optimum results are oba n 'l by making the distance 7; approximately equal to the average diameter of the coil sec tions S and S With this spacing of the coil sections the self-inductance of thecoil system is approximately only 20% less than the sum of the self-inductances of the two coil sections S and S alone, in spite of the fact that'the fluxes of said coil sections are oppositely directed, l have found that this spacing of the coils produces substantial magnetic decoupling of the system. l have found by empirical determination that a greater spacing between the coil sections does not produce an increase in self-inductance commensurate with the loss of the magnetic decoupling characteristic produced thereby, and that conversely, a closer spacing of the coils produces too great a reduction in the self-inductance of the system without a correspondingly net gain in the magnetically decoupling characteristic. in other words, where the coil sections are farther apart than the distance F), the coil system loses astaticism very rapidl and on the other hand where the coil sections are closer together than the distance (3, the useful inductance decreases rapidly on account of the rowth of the buckor reverse mutual of the coils.

l While ll show coil system composed of a single layer or" windings, I desire it to be understood that this is shown merely by way of simple explanation, and that the coil sections may comprise multi-layer windings, as disclosed for example in my copending application, Serial No. 195,631 filed May 31, 1927.

rVhere multi-layer windings are used, the optimum results are obtained when the coil sections S and S are separated by a distance equal to the average diameter of a coil section, the separation between the coils being considered as the separation between the centers of the coil sections.

The primary coil P of the coupling apparatus is a simple short solenoid of larger diameter than the secondary S, and is arranged to pivot on the axis 0 to swing through the are indicated by the arrowed line a, y in the figure. In the position 0, y the coupling between the primary and secondary is at a minimum (substantially zero) because the primary is arranged in the space between the two coil. sections S and S and the said primary couples equally and difierentially with the two coil sections S and S of the secondary. In the position 0, a, the primary P has a maximum coupling with the secondary S since the coupling to the coil section S is a maximum and the reverse coupling to the coil section S is substantially zero. By means of this arrangement I am enabled therefore to provide a coupling system having a very wide range of variation, from a minimum which is substantially zero to a fairly high maximum, although the coil sys tem S is designed to be substantially magneticaily decoupled from surrounding apparatus;

The manner of connecting the coil system and coupling apparatus to adjacent tubes of a radio receiving set is indicated in the figure, the primary P connecting the plate of one tube to the 13+ side of the battery, and the secondary coil system S connecting'the grid of the next succeeding tube to ground. The specific manner in which the apparatus of my present invention may be used in radio r ceiving circuits is further shown in my aforesaid application Serial No. 123,346, of which the present application is a division.

The manner of designing and constructing a coil system and a transformer embodying the principles of my present invention will, in the main, be fully apparent from the above detailed description thereof; The uses and manifold advantages thereof, especially in radio frequency circuits of the tuned and selective types, will, it is thought, be also apparent from the above detailed description. l v hile l have shown and described my invention in the preferred form, it will be obvious many changes and modifications may be made in the construction disclosed without departing from the spirit of the invention, defined in the following claims,

I claim:

1. A coupling apparatus comprising a secondary including a plurality of electrically connected coil sections, said coil sections being wound and connected to produce oppositely directed fluxes of substantially equal magnitudes and being spaced apart a distance to produce a resulting self-inductance of substantial ma itude, the arrangement of the fluxes and t e spacing of the coil sections producing substantially neutralizing magnetic fields at a distance; and a primary coupled to said secondary, said primary comprising a coil movable between the coil sections of the said secondary from a position of'equal and opposite coupling to the coil sections to a position of differential coupling therewith.

2. A coupling apparatus comprising a secondary including a plurality of electrically connected coil sections, said coil sections being wound in opposite directions to produce oppositely directed fluxes and being spaced axially a distance apart to produce a result ing inductance of substantial magnitude, the spacing between and the product of the number oi turns and area of each of said oppositel wound coil sections being such as to .pro uce substantially neutralizing magnetic fields at a distance; and a primary differentially coupled to the coil sections of said secondary.

3. A coupling apparatus comprising a secondary including a plurality of electrically connected coil sections, said coil sections being wound in opposite directions to produce oppositely directed fluxes and being spaced axially a distance apart to produce a resulting inductance of substantial magnitude, the spacing between and the product of the num ber of turns and area of each of said oppositely wound coil sections being such as to produce substantially neutralizing magnetic fields at a distance; and a primary coupled to said secondary, said primary comprising a coil movable between the coil sections of said secondary from a position of equal and opposite coupling to the coil sections toa position of differential coupling therewith.

4. A coupling apparatus comprising a secondary including a pair of electrically connected coil sections, said coil sections being wound in opposite directions and being spaced axially a distance apart to produce a resulting inductance of substantial magnitude, the product of the number of turns and area of one coil section being substantially equal to the product of the number of turns and area of the other coil section and the distance between the coil sections being substantially equal to the diameter of a coil section, whereby substantially neutralizing magnetic fields at a distance are produced; and a primary difl'erentially coupled to the coil sections of said secondary.

thecoil sections of said spaced axially a distance apart to produce a resulting inductance of substantial magnitude, the product of the number of turns and area of one coil section being substantially equal to the product of the number of turns I and area of the other coil section and the distance between the coil sections being substantially equal to the diameter of a coil section whereby substantially neutralizing magnetic fields at a distance are produced; and a primary coupled to said secondary, said primary comprising a coil movable between the coil sections of said secondary from a position of equal and opposite coupling to the coil sections to a position of differential coupling therewith.

6. A coupling apparatus comprising an inductance including a plurality of electri cally connected coil sections, said coil sections being wound and connected to produce oppositely directed fluxes of substantially equal magnitudes and being spaced apart a distance to produce a resulting self-indud tance of substantial magnitude, the arrange ment of the fluxes and the spacing of the coil sections producing substantially neutralizing magnetic fields at a distance; and another inductance difl'erentially coupled to first named inductance. p

7 A coupling apparatus comprising an inductance including a plurality of electrically connected coil sections, saidcoil sections being wound and connected to produce oppositely directed fluxes of substantially equal magnitudes and being spaced apart a distance. to produce a resulting self-inductance of substantial magnitude, the arrangement or the fluxes and the spacing of the coil sections producing substantially neutralizing magnetic fields at a distance; and another inductance coupled to said first named inductance, said second named inductance comprising a coil movable between the coil sections of the said first named inductance from a position of equal and opposite coupling t0 the coil sectionsto a position of differential coupling therewith.

8; A coupling apparatus comprising an inductance including a plurality of electri-' cally connected coil sections, said coil sections being wound in opposite directionsto prodiice oppositely "directed fluxes and being'spaced axially a distance apart to produce a resulting inductance of substantial magnitude, the spacing between and the product of the number of turns and area of each of said oppositely wound coil sections being such as to produce substantially neutralizing magnetic fields at a distance; and another inductance difierentially coupled to the coil sections of said first named inductance.

9. A coupling apparatus comprising an inductance including a plurality of electrically connected coil sections, said coil sections being wound in opposite directions to produce oppositely directed fluxes and being spaced axially a distance apart to produce a resulting inductance of substantial magnitude, the spacing between and the product of the number of turns and area of each of said oppositely wound coil sections being such as to produce substantially neutralizing magnetic fields at a distance; and another inductance coupled to said first named inductance, said second named inductance comprising a coil I movable between the coil sections of said first named inductance from a position of equal and opposite coupling to the coil sections to a position of difierential coupling therewith. 10. A coupling apparatus comprising an inductance including a pair of electrically connected cdil sections, said coil sections being wound in opposite directions and being spaced axially a distance apart to pl'ouucx; resulting inductance of substantial magnitude, the product of the number of turns and area of one coil section being substantially equal to the product of the number of turns and area of the other coil section and the distance between the coil sections being substantially equal to the diameter of a 001i sec: tion, whereby substantially neutralizing magnetic fields at a distance are produced; and another inductance differentially coupled to the coil sections of said first named inductance. i

11. A coupling apparatus comprising an inductance including a pair of electrically connected coil sections, said coil se'ctions being wound in opposite directions and being spaced axially a distance apart to produce a resulting inductance of substantial magnitude, the product of the number of turns and area of one coil section being substantially equal to the product of the number of turns and area of the other coil section and the distance between the coil sections being substantially equal to the diameter of a coil section whereby substantially neutralizing magnetic fields at a distance are produced; and

another inductance coupled to said first named inductance, said second named inductance comprising a coil movable between the coil sections or said first namedinductance from a position of equal and opposite coupling to the COll sections to a position of differential coupling therewith.

Signed at New York city, in the county of New York, and State of New York this 20th day of September, A. D. 1927.

LESTER L. JONES. 

